Sustained effects of plasma norepinephrine levels on femoral-radial pressure gradient after cardiopulmonary bypass

In order to determine the influence of the sympathetic nervous system upon the femoral-radial artery pressure gradient after cardiopulmonary bypass (CPB), we examined plasma norepinephrine levels in 34 adult male patients undergoing coronary artery bypass grafting. Cardiovascular parameters, including systolic arterial pressure, mean arterial pressure, cardiac index (CI), systemic vascular resistance index (SVRI), pulmonary artery pressure (PAP), hemoglobin (Hb) and peak dP/dt of radial and femoral artery pressures were measured after sternotomy, and immediately after the discontinuation of CPB and 90min after CPB. Plasma norepinephrine levels were measured after sternotomy, after aortic declamping and 90min after CPB.The patients were divided into two groups. Group A consisted of 17 patients whose femoral minus radial systolic pressure difference was 15mmHg or more at 90min after CPB, while Group B consisted of 17 patients with the difference less than 15mmHg. Group A patients had significantly longer time values in the duration of both CPB (Group A 175 ± 10min; Group B 115 ± 12min, P 0.001) and aortic cross clamping (Group A 116 ± 7min, Group B 71 ± 9min, P 0.001).Although there was no significant difference in Hb or PAP of 90min after CPB in Groups A and B, the following values, listed in the order of A to B, were obtained; CI, 2.79 ± 0.10 versus 3.46 ± 0.16l·min^–1·m^–2 (P 0.01); mean radial artery pressure (MRP), 58.7 ± 2.4 versus 65.1 ± 1.8mmHg (P 0.05); peak dP/dt of radial artery pressure, 568 ± 64 versus 1026 ± 61mmHg·sec^–1 (P 0.001); and plasma norepinephrine concentration, 1.81 ± 0.25 versus 0.98 ± 0.10ng·ml^–1 (P 0.01), which were statistically significant.The higher femoral-radial artery pressure gradient after CPB was observed in patients with both a longer CPB time and a higher plasma norepinephrine concentration. These results suggest that a marked constriction of peripheral arteries might have produced a damped transmission of the pressure pulse to the radial artery.(Nakayama R, Goto T, Kukita I, et al.: Sustained effects of plasma norepinephrine levels on femoral-radial pressure gradient after cardiopulmonary bypass. J Anesth 7: 8–15, 1993)